Please, for the love of this game do not add ranked to this. It's popular, it's fun but please don't implement it yet, it's just still very buggy, still full of balance issues and other things that need time and attention to them. By adding ranked to this it's just gonna create a huge s**tstorm of frustrated players.
This is too new and I personally think by slapping the ranked system of normal league into it it's just gonna cause a lot of problems. This is a whole new game, it's not league as we know and love it. So please, again, take your time to think about it, it's the only moment when you can stop what is about to come without a lot of repercussions. The game is far from being polished or done by any mean so again my point here stands, why add ranked?